<!--The content below is only a placeholder and can be replaced.-->
<nav>
  <dl *ngFor="let first of nav">
    <dt>{{first.name}}</dt>
    <dd>
      <!-- 二级导航 -->
      <dl *ngFor="let second of first.next">
        <dt>{{second.name}}</dt>
        <!-- 三级导航 -->
        <dd *ngFor="let third of second.next">{{third.name}}</dd>
        <!-- 三级导航结束 -->
      </dl>
      <!-- 二级导航结束 -->
    </dd>
  </dl>
</nav>

<input #box (keyup)="0">
<p>{{box.value}}</p>

